I know this is old and you may have solved your issue but hoping that this might help someone else in the future.
I had the same issue and I can confirm that command from Github works fine:
We have a user base of over 20k and use ldap sync. And after each sync the http_logs table was increasing quite a bit.
Just make sure after you run that command, to perform a vacuum in psql (vacuum verbose http_logs)
if autovacuum is not enabled (should be by default).
Once the vacuum is done, you should get the space back. Hope this helps if there is someone else who is having smilar issues.
Also, you are right, it would be nice to be able to control how much of the ldap stuff is being logged.